Quad Marker Screening Test

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

Charles Patrick Davis, MD, PhD

Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

What is the quad marker screening test?

The quad marker screening test (quad screen) is a blood test administered in
pregnancy, typically between the 15th and 20th weeks of gestation. Similar to
the triple screen, the quad marker screen provides information about whether
there is an increased risk for certain birth defects in the baby. The test is
simple and involves taking a blood sample as for any other routine blood test.
The quad marker test is a screening test, meaning that it gives information
about risk, but it does not allow the definitive diagnosis of any conditions. It
can only signal that further testing should be done to confirm a diagnosis.
There is no risk to the baby from the test.

What substances are measured in the test?

The quad screen looks at the three substances also measured in the triple
screen (alpha-fetoprotein, human chorionic gonadotropin, and estriol) test plus
one additional substance, inhibin A.

Alpha-fetoprotein (AFP) is produced by
the liver of the fetus

Human chorionic gonadotropin (hCG) is a
hormone made by the placenta

Estriol is an estrogen made both by the
placenta and the liver of the fetus

Inhibin-A is another hormone made by
the placenta

Looking at levels of these four substances in the mother's bloodstream allows
an estimation of risk for neural tube defects and certain chromosomal
abnormalities, like Down syndrome.